Welcome to the AC Tropical Fish aquarium forum. Our aquarium forum is the place to discuss any aquarium related issue in a friendly environment. Our aquarium forum welcomes aquarists of all levels from beginners to experts. Please ask a question in the how to section of our forum or read the FAQ section if you have any questions. register to and become a part of our friendly aquarium forum community today.

Stocking question

0

I'm in the process of stocking my 20 gallon tank. Right now I have 6 mystery snails (averaging about an inch each right now, but I know they will grow), three black kuhli loach, three long finned zebra danios, three black skirt tetras, and I plan on getting one sunburst wag platy soon.

Really I'm wanting to know more about stocking a tank. I know that there rule for beginners of "1 inch of fish per gallon" and I tried to follow that. I have 21 inches of full grown fish in a 20 gallon tank (my fish aren't full grown though, I've just got them). I've also been told that snails don't contribute to the load on a tank but I'm figuring out that doesn't seem correct as my snails seem to produce a decent bit of waste. I do keep an eye on the water parameters though and they seem good. Anyway, while reading up on stocking a tank I read that it has to do with bio-load of fish taking oxygen and putting carbon dioxide and waste into the tank.

My question is does the fact that I have a bubbler, a filter and do regular water changes make it so that I can stock my tank more than normal? Or is all of that expected under the "1 inch of fish per gallon" rule. What are more advanced rules of tank stocking?

Stocking an aquarium involves much more than just the size of the fish. The "inch of fish per gallon" guide may work with small fish but is only one part of the issue and very misleading at that.

The species of fish is of prime importance. Not only their maximum mature size, but their level of activity; active swimming fish must have more physical space than sedate fish of the same body size. The needs of the species is involved: shoaling fish must be in groups. The natural behaviours of the fish species are part of this: feisty or more aggressive fish will demand more space, and will also affect other species. The filtration obviously plays into it too. And the presence of live plants. The environment is critical; environment meaning the water parameters, and the aquascape, because fish have fairly specific requirements in both areas. Then there is the tank shape; longer or wider tanks have more surface area, and can support more life than tall tanks of the same volume.

All of the afore-mentioned factors directly affect each other too. So you can see why a hard and fast rule of any sort is next to impossible.

Turning to your specific situation, you have no room for different species, because you have problems with the danio and tetra. These are shoaling fish and must have a group; six is usually said to be minimum, but more is always better if space permits. The danio is an active swimmer, so needs more room right off the bat. And the black skirt tetra is not a small fish, growing to over 2 inches with some sources suggesting up to three inches; with six of these, you may have close to 18 inches of fish, so you can see what this does to the "rule." In a 20g, I would remove one of these two species.

There is also the problem of fin nipping from the black skirt tetra, especially when confronted with the temptation of long-fin danio; and when kept in small numbers, or in small spaces (to the fish), this nipping can be increased out of frustration. This is an example of what I meant by the behaviours of each fish species being a factor.

Hope this helps explain things; feel free to question.

Byron.

Byron Hosking, BMus, MA
Vancouver, BC, Canada

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

What you might want to do is return the danios (as B said, they require a larger tank as they are fast and active swimmers + the black skirts will start nipping them) and up your school of black skirts to 6 which would hopefully keep them from nipping each other.
You could then get 3 platies if color is what you're looking for, making sure to get 2 females and 1 male so the male doesn't over hassle the females or all males or all females. Be prepared for fry if you have both sexes but most likely the parents or the black skirts will eat them and keep the population under control.

I have 21 inches of full grown fish in a 20 gallon tank (my fish aren't full grown though, I've just got them). What are more advanced rules of tank stocking?[/QUOTE]

As stated above, if your fish aren't full grown, you are very overstocked right now - only fish that grow to an inch apply to that rule - consider whether you would put a 10in fish into a 10 gal tank - that' doesn't work.

Fish need to be housed according to their needs - schooling fish in larger #'s, some fish need a male to several females, etc.

It's nice to want a tank chock full of fish, but that isn't fair to them to make them cramped together - can lead to aggression and poor water quality no matter how often you change the water.

I have 21 inches of full grown fish in a 20 gallon tank (my fish aren't full grown though, I've just got them). What are more advanced rules of tank stocking?

As stated above, if your fish aren't full grown, you are very overstocked right now - only fish that grow to an inch apply to that rule[/QUOTE]

I have 21 inches of fish once they are full grown. I don't have 21 inches of fish right now, they are still young and small. And I get that I don't have a big enough school of fish now, in either group. I suppose I'll take one species back to the store (probably the tetra's, I like the danios much more). I don't understand what you mean by "only fish that grow to an inch apply to that rule" So your saying if I had a 10 gallon tank I couldn't have three platy's in it that get to be 3" each? I would like to have a fuller looking tank but I certainly don't want to do harm to my fish. I certainly understand that in small tanks you should have small fish. I know you wouldn't want to put a 20" fish in a 20 gallon tank, that'd be ridiculous, but that's not to say that I can't have fish larger than an inch.

Also I did make sure to get a 1/3 ratio of males to females for all my species.

In terms of my tank I have two hides for the fish (one rock like hide and one stump like hide, and moderate planting. Fake silk plants only) I like the idea of having real plants, but I got some once and none of them would sprout. That was a while ago though, before I started testing my water and such.

Any tips on growing aquarium plants?

Also still haven't heard anything about the snails and if they do in fact contribute to how many fish I can have.

As stated above, if your fish aren't full grown, you are very overstocked right now - only fish that grow to an inch apply to that rule

I have 21 inches of fish once they are full grown. I don't have 21 inches of fish right now, they are still young and small. And I get that I don't have a big enough school of fish now, in either group. I suppose I'll take one species back to the store (probably the tetra's, I like the danios much more). I don't understand what you mean by "only fish that grow to an inch apply to that rule" So your saying if I had a 10 gallon tank I couldn't have three platy's in it that get to be 3" each? I would like to have a fuller looking tank but I certainly don't want to do harm to my fish. I certainly understand that in small tanks you should have small fish. I know you wouldn't want to put a 20" fish in a 20 gallon tank, that'd be ridiculous, but that's not to say that I can't have fish larger than an inch.

Also I did make sure to get a 1/3 ratio of males to females for all my species.

In terms of my tank I have two hides for the fish (one rock like hide and one stump like hide, and moderate planting. Fake silk plants only) I like the idea of having real plants, but I got some once and none of them would sprout. That was a while ago though, before I started testing my water and such.

Any tips on growing aquarium plants?

Also still haven't heard anything about the snails and if they do in fact contribute to how many fish I can have.

You aren't listening to those with more knowledge than yourself. Your stocking list doesn't work. And snails have a big bioload and have a big influence on what fish you can have.

You aren't listening to those with more knowledge than yourself. Your stocking list doesn't work. And snails have a big bioload and have a big influence on what fish you can have.

I'm trying to listen, I don't understand. I am going to take back my tetra's so I'll have a larger school of danio's which will make them more happy. Someone said though that if I take back one species of fish I could get three play's which seems like with my current stocking adding that many more fish is a bad idea. I know snails have an influence on what fish I can have. I was looking at getting semi aggressive fish but decided I couldn't without stressing or possibly killing my fish.

I think perhaps there was a misunderstanding and some read your post as stating you currently have 21 inches of fish - not that your fish will eventually grow to = 21 inches - and that you wanted to add more. That is probably what the 'not listening' comment referred to.

You are clearly attempting to figure out the best thing to do - and good for you - and I can see that you are listening.

If you like the danios then keep them, add 3 more and return the black skirts. Danios do prefer more swimming space but I recently read a profile on long fin zebra danios that indicated a 10 gal tank was minimum so you should be okay with the 20 gal.
Some may feel that adding 3 platies may be pushing it a bit but I would be comfortable adding them as long as you keep up on your weekly 50% water changes, monitor your ammonia, nitrites and nitrates and keep them in check and don't add any more fish since the tank would then be fully stocked.
Those are large snails. Yes they produce some bioload. but if, when you do your weekly water changes, you also vac at least 1/2 of your substrate, you should be able to keep the nitrates in check (meaning less than 20ppm)
Do you have an API liquid water test kit? if not, you need one so you can monitor your water parameters. Also, what kind of filter(s) are you using and what are they rated for? More filtration = better, cleaner water and is better for the fish. Most rec you have double filtration. So if you have a filter rated for a 20 gallon tank, you should get another filter rated for a 20 gallon. Make sense?

I'm trying to listen, I don't understand. I am going to take back my tetra's so I'll have a larger school of danio's which will make them more happy. Someone said though that if I take back one species of fish I could get three play's which seems like with my current stocking adding that many more fish is a bad idea. I know snails have an influence on what fish I can have. I was looking at getting semi aggressive fish but decided I couldn't without stressing or possibly killing my fish.

What did I say to make it seem like I wasn't listening?

I sincerely apologize - I misread your post, didn't see the part about you returning the tetras.

I have a school of 8 longfinned zebra danios and they are very active swimmers and need more tank length than a 20 gal high provides. It is only 24 inches wide and they need a minimum of a 30 inch wide tank (a 20 gal long).

I'm trying to listen, I don't understand. I am going to take back my tetra's so I'll have a larger school of danio's which will make them more happy. Someone said though that if I take back one species of fish I could get three play's which seems like with my current stocking adding that many more fish is a bad idea. I know snails have an influence on what fish I can have. I was looking at getting semi aggressive fish but decided I couldn't without stressing or possibly killing my fish.

What did I say to make it seem like I wasn't listening?

I sincerely apologize - I misread your post, didn't see the part about you returning the tetras.

I have a school of 8 longfinned zebra danios and they are very active swimmers and need more tank length than a 20 gal high provides. It is only 24 inches wide and they need a minimum of a 30 inch wide tank (a 20 gal long). Also, they need a minimum of 8-10 for a proper school.